Don't check for anonymous user access at index time.

[alxp]

Just removing the condition where the indexer bails if a media is not accessible to Anonymous. We have implemented passing auth headers to Mirador, see this Draft PR: Islandora/islandora_mirador#32

[adam-vessey]

The visibility of content in the Solr index is related more to who that index will/can be used by, and not so much what other services might make use of its results. As in: Because the index is usable by anon, there should not be anything in it that cannot be accessed by anon to avoid potentially leaking data via the index.

That said, things could potentially be made toggleable via configuration if admins are comfortable with doing so, as in, something like: https://github.com/discoverygarden/islandora_hocr/compare/feature/skippable-access-check ?